/**
* Iterates over the predecessors of this instruction, and merges all the post-instruction
* register types for the given register. Any dead, unreachable, or odexed predecessor is ignored
*
* @param registerNumber the register number
* @return The register type resulting from merging the post-instruction register types from all
* predecessors
*/
protected RegisterType mergePreRegisterTypeFromPredecessors(int registerNumber) {
RegisterType mergedRegisterType = null;
for (AnalyzedInstruction predecessor : predecessors) {
RegisterType predecessorRegisterType = predecessor.postRegisterMap[registerNumber];
assert predecessorRegisterType != null;
mergedRegisterType = predecessorRegisterType.merge(mergedRegisterType);
}
return mergedRegisterType;
}
/*
* Merges the given register type into the specified pre-instruction register, and also sets the post-instruction
* register type accordingly if it isn't a destination register for this instruction
* @param registerNumber Which register to set
* @param registerType The register type
* @returns true If the post-instruction register type was changed. This might be false if either the specified
* register is a destination register for this instruction, or if the pre-instruction register type didn't change
* after merging in the given register type
*/
protected boolean mergeRegister(
int registerNumber, RegisterType registerType, BitSet verifiedInstructions) {
assert registerNumber >= 0 && registerNumber < postRegisterMap.length;
assert registerType != null;
RegisterType oldRegisterType = preRegisterMap[registerNumber];
RegisterType mergedRegisterType = oldRegisterType.merge(registerType);
if (mergedRegisterType.equals(oldRegisterType)) {
return false;
}
preRegisterMap[registerNumber] = mergedRegisterType;
verifiedInstructions.clear(instructionIndex);
if (!setsRegister(registerNumber)) {
postRegisterMap[registerNumber] = mergedRegisterType;
return true;
}
return false;
}
